Paste the following command: softwareupdate --fetch-full-installer --full-installer-version 10.15.7

For users on Windows or those who need a pre-built DMG file, specialized tools can help:

Apple does not provide a direct DMG download link on its main website; instead, it offers the installer through the App Store or Terminal. 1. The Official App Store Method (Recommended)

The full installer will download directly into your folder. 3. Third-Party Tools and Scripts

: For older machines with limited RAM (4GB–8GB), Catalina often runs smoother than more modern, resource-heavy updates.

: A Python-based tool available on GitHub that downloads macOS installer files directly from Apple's servers. It can help you obtain the base files needed to create a DMG.